1. Field of the Invention
The present invention pertains to the field of audio loudspeakers using a piezoelectric device as a driver, and more particularly to a resonance damper for use on such a piezoelectric device.
2. Description of the Related Art
Modern piezoelectric devices are a very reliable and inexpensive means of converting electrical energy into physical motion and exhibit a high tolerance to environmental factors such as electromagnetic fields and humidity.
Accordingly, piezoelectric devices are a logical choice for use in audio transducers. However, to date no one has been able to construct a practical piezoelectric audio loudspeaker having good fidelity characteristics. Although piezoelectric devices have a good frequency response, designers have had limited success in coupling a piezoelectric device to an acoustical diaphragm for producing sound in the manner that produces a high fidelity speaker or microphone. Conversely, piezoelectric devices have been successfully used in audio transducer devices that produce a single or a limited range of frequencies, such as beepers and audio warning signals associated with electronic devices.
One aspect of audio loudspeaker quality can be quantified by its Q factor, which represents the degree to which the speaker components, such as the driver, diaphragm and enclosure, interact to control resonance. Lower Q factors indicate a lower resonant frequency amplitude which is desirable, particularly for high-frequency speakers. Improved audio quality, without degradation of other performance parameters, is always a goal of loudspeaker designs.
A common failure mode of prior art piezoelectric transducers is failure of the connection between the piezoelectric device and the diaphragm due to rough handling or high-impact loads on the speaker enclosure. Attempts to shock mount the piezoelectric device typically resulted in reduced frequency response and poor speaker fidelity.
What is needed then is a resonance damper that improves the Q factor and frequency response of the driver. It is also desirable to provide a means for shock mounting the piezoelectric driver used in audio loudspeakers without affecting the overall fidelity of the loudspeaker.